I love my my new Harman Accentra 52i insert. But I'm embarrassed to admit I was pouring pellets into the hopper when the plastic bag touched the glass and melted some plastic onto the glass. I'm afraid to scrape or use an abrasive, but water, vinegar and rubbing don't remove the smeared residue. Does anyone have any ideas how I might remove it? (I've since gotten a hod, which makes life so much better.)